ES2525044T3 - Procedure for the treatment of water with chlorine dioxide - Google Patents

Abstract

Procedure for the treatment of water with chlorine dioxide (ClO2), characterized by the characteristics that 1. the reaction room, in which ClO2 is produced, is completely surrounded by water, 2. the water surrounding the room reaction is at the same time the water to be treated, 3. the ClO2 resulting in the reaction room is moved from the reaction room directly to the water to be treated, the reaction room being a reactor, which is it operates without any pressure regulation arrangement, and by providing the reactor with a free outlet located in the outlet orifice from the reactor, such that the pressure in the reaction chamber can only rise to the value that is exerted by the surrounding water over the reaction room.

Description

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DESCRIPTION

Procedure for the treatment of water with chlorine dioxide

The invention relates to a process for the treatment of water with chlorine dioxide (ClO2).

Chlorine dioxide, because of its high bactericidal, virucidal and algicidal effect, is used in water treatment. Because of the tendency to explode a gaseous chlorine dioxide (c> 300 g / m3) and chlorine dioxide solutions (c> 26 g / l), a chlorine dioxide cannot be stored in a form compressed or in solutions with higher concentrations. Because of these chemical properties, chlorine dioxide must be produced at the site of its use. This is done by mixing the basic chemicals in special reactors of facilities for the production of chlorine dioxide. The reserve containers for chemical products, the dosing arrangements as well as the reactor of the installations for the production of chlorine dioxide form a locally coherent, aparative unit, which is generally placed in enclosures that are traveled by people.

There are several procedures, but mainly three fundamental ones, for the synthesis of ClO2, which are used commercially for water treatment. These procedures use sodium chlorite (NaClO2) as one of the starting materials. The fundamental chemistry of the three procedures is explained below. The substances used in this case are designated as starting chemicals or also reactants.

1. Procedure with sodium chlorite and a strong acid

In the first procedure a strong acid is used in common with sodium chlorite. Strong acid is in most cases hydrochloric acid or sulfuric acid. Mediating the use of hydrochloric acid, the stoichiometry of the reaction is as follows:

5 NaClO2 + 4 HCl → 4 ClO2 + 5 NaCl + 2 H2O

In addition to this, chlorine dioxide can be formed by using sulfuric acid, in a manner corresponding to the subsequent reaction:

10 NaClO2 + 5 H2SO4 → 8 ClO2 + 5 Na2SO4 + 2 HCl + 4 H2O

2. Procedure based on sodium chlorine and chlorine

This procedure uses gaseous chlorine in common with sodium chlorite. The reaction takes place in two stages, first with the formation of hydrochloric acid.

Cl2 + H2O → HOCI + HCl

The intermediate product, hypochlorous acid (HOCI), then reacts with sodium chlorite mediating formation of chlorine dioxide (ClO2).

HOCI + HCl + 2 NaClO2 → 2 ClO2 + 2 NaCl + H2O

The stoichiometric reaction that results from the two equations is

Cl2 + 2 NaClO2 → 2 ClO2 + 2 NaCl

3. Procedure that starts from sodium chlorite and sodium hypochlorite

In the third procedure, sodium hypochlorite (NaOCl) is used in common with sodium chlorite:

NaOCl + HCl → NaCl + HOCI

HCl + HOCI + 2 NaClO2 → 2 ClO2 + 2 NaCl + H2O

Synthetic reactions for the production of chlorine dioxide are generally carried out in reactors, which are operated either continuously or according to the batch procedure (batch English) or discontinuous.

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Two explosion limits should be taken into account in the case of chlorine dioxide production: More than 6 g of ClO2 / l of the solution [in contact with air] and more than 26 g ClO2 / l of the solution [decomposition typical of the aqueous solution]. In cases of chlorine dioxide syntheses carried out according to procedures 1 to 3, a dilution water is added to the reaction site in the case of the use of starting chemicals, which in the enclosure of reaction would lead to a concentration greater than about 26 g of ClO2 / l, in order to remain below this concentration of spontaneous self-decomposition. The chlorine dioxide solution that leaves the reaction room, which generally contains 20 or less g of ClO2 / l, is diluted with another stream of water to concentrations approximately smaller than 3 g ClO2 / l of the solution.

So that the procedures belonging to the state of the art can be made to work with satisfactory results as regards the safety of the facilities, the chlorine dioxide yield and the production yield that is specific for the time, they carry out different technical variations of procedures, among others, -The use of diluted starting chemicals: It falls below the concentrations of the

Chlorine dioxide solution that has been produced, in ones that are smaller than 26 g / l or respectively

smaller than 6 g / l. -The generation of a depression in the reactor through the application of a vacuum: It reduces the

concentration of chlorine dioxide in the gas phase at <300 g / m3. -The generation of an overpressure in the reactor, eg through the use of maintenance valves

of the pressure at the exit site from the reactor: The formation of a gas phase is prevented by

exceeding the solubility limit of chlorine dioxide; performance rises. -The use of discontinuous procedures with long periods of reaction time: The

performance in the case of the use of diluted starting chemicals. -The use of higher than stoichiometric amounts of acid in the case of the procedure with a

chlorite and an acid, and the use of amounts greater than stoichiometric chlorine in the case of a

Chlorite and chlorine procedure: yield is increased.

Despite the use of these procedural modes, it can be achieved in the case of operation that is not in accordance with the provisions of the chlorine dioxide production facilities, eg due to a dilution water deficiency; or due to a failure in the regulation of the pressure, a spontaneous decomposition (explosion) of the chlorine dioxide, or the chlorine dioxide, can be achieved, due to lack of tightness or breakage of the separation surfaces between the solution containing Chlorine and the environment, can lead to hazards in the environment of production facilities. Also the use of diluted starting chemicals, which lead to solutions of chlorine dioxide with a concentration smaller than 6 g / l, and consequently to the renunciation of higher production yields that are specific for time of the chlorine dioxide production facilities, it cannot exclude the danger to the environment of the production facilities due to the exceeding of the value of the MAK (maximum concentration in the workplace) of 0.1 ppm in the case of an operation that is not in accordance with the stipulations. In order to minimize these hazards, different technical measures are carried out at the actual production facilities, as well as at the installation sites of the chlorine dioxide production facilities, eg expensive conservation work in the production facilities, including the regular replacement of the reactors, isolated installation sites in the space for the production facilities, forced ventilation and air monitoring of the atmosphere of the placement sites through continuous gas analysis .

In order to counteract these problems, there are already first starting points in the state of the art that consist of arranging the reactors for ClO2 at least partially below water: Thus, US Pat. US4534952A discloses a process for the treatment of water with chlorine dioxide, in which the reaction room, in which chlorine dioxide is produced, is surrounded by water; in which case the water surrounding the reaction room is at the same time the water to be treated and in which case the chlorine dioxide resulting in the reaction room is moved from the reaction room directly to the water that is It has to try.

The reaction chamber (reaction chamber 34) extends in the case of the reactor shown in Figure 2 of document D5 from a mixing chamber (mixing chamber 50) until it reaches the outlet orifice (outlet bore 42). The water 18 to be treated circulates in the essential along the tubular conduit 20, so that approximately 2/3 (= two thirds) of the reaction room 34, 50 are surrounded by the water 18 to be try. For the rest, it is expected that an inactive eddy water will penetrate the flange mouth (pipe extension 70) until it reaches the sealing site between the two flanges 68 and 46. In this case, it will penetrate up to the gasket. tightness, drawn in Figure 2, which is sandwiched between the two flanges 46 and 68 and is designated in the specification (column 6, lines 38 to 42) with the name of "angular gasket 71".

However, in the mixing chamber 50 a synthesis of chlorine dioxide is already taking place, since the educts (starting products) provided here (compare column 5, lines 55 to 68) are very reactive ("capable of rapid generation of chlorine dioxide ”, column 4, line 38).

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Italian patent document IT-1351156 discloses in its Figures 1 and 2 a device for the treatment of water with chlorine dioxide, in which the reaction chamber R1, in which chlorine dioxide is produced, is completely surrounded by the water, and the water surrounding the reaction chamber R1 is at the same time the water to be treated.

However, in the case of this known device, chlorine dioxide, which has formed in the reaction room

5 (primary reactor R1 = primary reactor R1), is not directly displaced to the surrounding water to be treated, but is first diluted in a secondary reactor (secondary reactor R2), in which the chlorine dioxide is diluted with a water that does not correspond to the surrounding water to be treated.

The "oxidation / disinfection product" is formed in the secondary reactor R2 by dilution of the chlorine dioxide that has been synthesized in the primary reactor R1 with a dilution water.

10 The mission of executing chlorine dioxide water treatment in a safer and more efficient manner is established. In particular, the mission of minimizing the potential for danger in this way of carrying out the water treatment is established, in the case of a high production yield, specific for the time, of the chlorine dioxide production process, and when at the same time reduce the expense for security provisions.

A safe procedure had to be found for the environment and for people mediating avoidance of

15 the output of ClO2 into the environment, particularly in the enclosures, in which the installation is operated in a usual manner. At the same time, the advantages that are established through the use of concentrated starting chemicals such as, for example, the transport of a smaller amount of substances, of a higher reaction rate, of higher yields and a smaller reactor volume.

An object of the invention is a process according to claim 1.

Preferred improvements of the invention are set forth in the dependent claims.

A particularly preferred improvement of the invention consists in a process for the treatment of water with chlorine dioxide, which is characterized by the characteristics that

1. The reaction enclosure, in which ClO2 has been produced, is a reactor provided with a free outlet without any provision for pressure regulation, and this is totally surrounded by water,

2.

the water surrounding the reaction room is at the same time the water to be treated,

3.

The ClO2 that has resulted in the reaction room is moved from the reaction room directly to the water to be treated, the combination of the concentrations of the starting chemicals and possibly the dilution water that has been used being chosen , in such a way that the

The concentration of chlorine dioxide formed at the exit site from the reactor is located at a value greater than 3 g / l of the solution, preferably greater than 26 g / l of the solution and especially preferably greater than 80 g / I of the solution.

Another especially preferred improvement of the invention consists in a process for the treatment of

water with chlorine dioxide, which is characterized by the characteristics that

1. The reaction room, in which the ClO2 has been produced, is a reactor provided with a free outlet without any provision for pressure regulation, and this is totally surrounded by water,

2. The water surrounding the reaction room is at the same time the water to be treated, and it exerts on the solution containing chlorine dioxide, existing in the reaction room, a pressure with a magnitude such that it is not exceeds the limit of solubility of chlorine dioxide in water at a set temperature,

40 3. The ClO2 that has resulted in the reaction room is moved from the reaction room directly to the water to be treated, the combination of the concentrations of the starting chemicals and possibly of the dilution water being chosen. it has been used, so that the concentration of chlorine dioxide formed at the exit site from the reactor is located at a value greater than 3 g / l of the solution, preferably greater than 26 g / l of the solution and especially

45 preferred greater than 80 g / I of the solution.

Surprisingly, the problem posed by this mission could be solved through the technical measures of

according to the claims and the specification.

The characteristics 1 to 3 in their combination are essential in the invention for the present process, which

makes a safer job possible by avoiding the exit of ClO2 in work rooms or in the

50 environment and suppresses the negative repercussions of explosive decompositions. The reaction room, in which ClO2 is produced, is completely surrounded by water, and the water surrounding the reaction room is at the same time the water to be treated.

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The transfer of the chlorine dioxide formation site, outside the spaces traveled by people and the storage site of the starting chemicals, increases safety in a significant way. A lack of tightness, which can even cause explosions in the reaction room, is neutralized practically by the large volume of water.

The resulting ClO2 is displaced, bluntly, directly from the reaction room in which the ClO2 has been formed to the water to be treated, since the outlet orifice is located directly at the end of the reaction room and therefore it is also surrounded by the water to be treated.

It was also found, in a surprising way, that in the case of the combination of the use of concentrated starting chemicals with a dilution water eventually used, which lead to concentrations of chlorine dioxide in the reaction room that are more larger than 26 g / l of the solution and especially preferably larger than 80 g / l, no decomposition of the chlorine dioxide is reached, when the average period of residence in the reaction room is located at For a certain period of time, the formation of gaseous chlorine dioxide is prevented and the chlorine dioxide solution leaving the reaction room is suddenly diluted to concentrations in the region of milligrams. In addition, it was found that the necessary additional amounts greater than the stoichiometric amounts of an acid or respectively of chlorine, which increase the degree of conversion, can be decreased by an increase in the concentration of chlorine dioxide in the reaction room.

The advantages of the new procedure are explained in more detail hereafter.

A lack of tightness of the reaction enclosure, in particular of the reactor, can be managed in a simple and safe way in the water that circulates continuously in front of its wall. The chlorine dioxide that comes out in particular in the case of a lack of tightness of the reaction room, is diluted to a concentration that is not critical and is evacuated by transport. The same applies to the starting chemicals that eventually leave the reaction room, in particular the reactor. Since the synthesis of chlorine dioxide from concentrated starting chemicals can be carried out without any dilution by water, the necessary additional amounts greater than the stoichiometric of an acid or chlorine, which increase the degree of conversion, can be reduced , and additionally a significant elevation of the reaction rate is reached, a high specific production yield is established in the reaction room. By reducing the necessary average period of reagents' permanence in the reaction room, there is the possibility of minimizing the volume of the reaction room, with which it is possible, for example, the assembly of the reaction room, in particular of the reactor, within a tubular conduit, which is traversed by the water to be treated. In addition to this, from a safety technique point of view, an improvement in the relationship between the amount of chlorine dioxide that is permanently present in the reaction room during synthesis and the amount of water to be treated is established. .

The transfer of the chlorine dioxide formation site, from outside the spaces traveled by people and the storage site of the starting chemicals, increases safety in a significant way. Lack of tightness in the reaction room, which can even cause explosions in the reaction room, are neutralized practically by the large volume of water to be treated, in relation to the amount of chlorine dioxide that is present in The reaction room

Characteristics 1 through 3 in their combination are essential in the invention for the present process, which makes safe work possible, also mediating the use of concentrated starting chemicals without any dilution water, by avoiding the exit of ClO2 within work spaces or within the environment and suppresses the negative repercussions of explosive decompositions.

The reaction room, in which ClO2 is produced, is completely surrounded by water, and the water surrounding the reaction room is at the same time the water to be treated.

According to the invention, the use of a reactor as a reaction enclosure is provided.

According to the 3rd stage of the procedure, the resulting ClO2 is displaced, without detours or other additional conduits, directly from the reaction room, in which the ClO2 is formed, to the water to be treated, since the orifice The outlet is located directly at the end of the reaction room, preferably in the reactor, and is therefore also surrounded by the water to be treated. This technical measure is the preferred variant of the procedure.

Otherwise there is the possibility of transporting the chlorine dioxide solution that leaves from the reaction room, through a bypass line, which is located at the end of the reaction room (in the exit hole), to One or more other sites. This can be exploited among other things for a distribution of the chlorine dioxide solution in a large global system to be treated or to a subdivision

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in several individual systems that have to be treated. All the arrangements are suitable for the bypass line, with which the effects described above can be achieved, such as for example fixedly mounted pipes or flexible hose systems. Equipment for the distribution of the chlorine dioxide solution may also be placed at the end of the bypass line, eg a water tube pump for liquids, a recirculation pump, etc.

The expression "move it into the water to be treated" means that ClO2 is incorporated from the reaction room, preferably by means of the starting chemicals that enter the reaction room and eventually by means of of the dilution water that enters the enclosure, directly or through a bypass line, in the water to be treated.

The flow of renewal of the water to be treated in the outlet orifice of the reaction room, preferably in the outlet orifice from the reactor, or from the bypass line, can be increased by technical arrangements.

The reactor is operated according to the invention without any pressure regulation arrangement. By means of a free outlet through the end of the outlet orifice from the reactor, or bypass line, it is ensured that the pressure in the reaction chamber can only rise to the value, which is exerted by the surrounding water on the reaction enclosure

The concentration of chlorine dioxide that is formed in the reactor can be adjusted, in combination with the pressure and temperature of the surrounding water, such that the solubility limit of chlorine dioxide in water is not exceeded. In this way, the formation of a 2-phase system can be prevented by a phase of gaseous chlorine dioxide that is formed. The pressure, which is exerted by the water to be treated on the reaction site, can be modified, for example, by the immersion depth of the reactor in a water store. The pressure ratios for a reactor introduced in a tubular conduit can be influenced, for example, by means of blocking elements that are integrated in the tubular conduction.

If the water to be treated is renewed in the outlet orifice from the reactor with a corresponding flow rate, then the concentration of the chlorine dioxide solution leaving the reactor can suddenly be displaced to a region of milligrams. This can be achieved, for example, by the resource that the reactor is introduced into a tubular conduit, which is traversed by the water to be treated in an amount, which corresponds to the desired renewal flow.

A reactor immersed in a water store can be placed locally in the vicinity of the suction side of a recirculation pump, in order to ensure the corresponding flow of renewal of the water to be treated at the end of the exit site from the reactor or bypass line. If a recirculation pump is not present, a large number of procedures exist, according to the state of the art, using, for example, water tube pumps for liquids or other recirculation arrangements, which give rise to the desired flow rate of renewal. of the water to be treated at the end of the outlet orifice from the reactor or the bypass line.

In principle, all the chemical processes for the production of ClO2 can be used in the reaction room, in particular the 1st to 3rd procedures that have been described in the introductory part or also starting from a chlorate.

The process with hydrochloric acid and a chlorite (1.) is preferred in this invention. In such a case, the starting chemicals (reactants) based on a chlorite salt of an alkali metal, preferably sodium chlorite, may be present in aqueous solutions concentrated from 3.5% to 40%. The acid is preferably a hydrochloric acid in a concentration of 3.5% to 42%. In the case of the especially preferred embodiment of the invention, concentrated starting chemicals are used and working according to the process with hydrochloric acid and a chlorite (1.). The concentration of hydrochloric acid is then about 33-42% and that of the sodium chlorite solution is about 25-40%. No dilution of the starting chemicals is carried out in front of or inside the reaction room, preferably of the reactor.

The starting chemicals (reactants), in particular an acid and a chlorite, are displaced in the form of the aqueous solution, as described above, separately by means of the solutions' own pressure or with the help of pumps up to reaction room and are reacted.

In the case of the preferred mode of operation, the reactants are employed as concentrated solutions and the use of a dilution water is disregarded, such that the concentration of chlorine dioxide at the end of the reaction chamber, therefore at the exit site from the reactor, or from the conduction

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bypass, is adjusted to a value greater than 80 g / l of the solution. Alternatively, a dilution water may be used in order to adjust the concentration of chlorine dioxide at the exit site from the reactor, or in the bypass line, between a value greater than 3 g / l of the solution, of preferably more than 26 g / l of the solution and especially preferably more than 80 g / l of the solution.

The device for carrying out the process according to the invention essentially comprises appropriate devices and equipment. The device typically includes one or more deposits for the starting chemicals (reactants), in particular a storage tank for an acid and a storage tank for a chlorite, an aqueous solution of an acid being stored in the storage tank. the storage of an acid and a solution of an alkali metal salt of a chlorite ion in the storage tank for a chlorite. Equipment is provided that can both feed the appropriate components into the storage tanks and also remove solutions. Preferably, the equipment includes pumps and supply lines, which are sufficient to guarantee the flow rates of the starting chemicals (reactants) in particular of aqueous solutions of some acids and solutions of alkali metal salts of a chlorite ion, as well as the amount of dilution water. Those specialized in the sector can easily determine the appropriate sizes of the corresponding storage tanks, supply lines and pumps, in order to establish the necessary feed flow rates of the reactant solutions (ie e.g. Aqueous solutions of some acids and solutions of an alkali metal salt of a chlorite ion.

Preferably, the device has embodiments with at least two pumps for two starting chemicals (reactants), but in particular one for the solution of the salt of an alkali metal of a chlorite ion and the other for the aqueous solution of an acid, or three pumps, in case a dilution water is dosedly added.

The device further comprises equipment intended for mixing the solution of the starting chemicals (reactants), in particular of the solution, which contains the salt of an alkali metal of a chlorite ion, and the aqueous solution of an acid, in order to make available an aqueous reaction solution of the starting chemicals (reactants). Any equipment can be used, which sufficiently mixes the aforementioned solutions, including the usual T-pieces or other connecting elements, which combine in one to two streams or respectively to three streams, throttling conduits and / or a container with stirring system. The aqueous reaction solution can then be fed after mixing in the reaction room. Preferably, the mixing of the two reactants and the dilution water that has been used is carried out in the reaction room. The mixing process can be initiated by any arrangement, such as eg rebound plates, injectors or filler bodies, which guarantees optimum mixing.

As a reaction enclosure, a reactor of any type can be used, which is in a position to trigger the reaction between the starting chemicals (reactants), in particular the aqueous solution of an acid and the salt of an alkali metal of an ion of chlorite, including continuous reactors with stirring systems, simple tanks, mass or bowling circulation reactors and tubular reactors. A tubular reactor is especially preferred.

Normally, a chlorine dioxide production unit is composed only of a tubular reactor, but the production efficiency of a unit can be increased by the parallel arrangement of several reactors, for example to form a tube bundle. The reactor can both be temperature regulated and also be composed of a material that conducts heat well, in order to deliver the heat of reaction that is released to the surrounding water. The work material, based on which the reactor is manufactured, is made up of materials that have good stability against the respective reaction solutions. In the case of the production of chlorine dioxide solutions with concentrations greater than 28 g / l, they are used as the material for the reactor, for example titanium, the Alloy 31 alloy, glass or work materials for chemical processes, e.g. eg polymers such as eg a PVDF or PTFE. ClO2 is evacuated from the reactor by an arbitrary mechanism, which is in a position to evacuate the aqueous solution from a reactor. Preferably, the reaction is carried out in a continuous manner, and ClO2 is evacuated from the reactor in a continuous manner. After leaving the reactor, ClO2 is added in a dosed manner directly to the water to be treated or transported, through a bypass line that is located in the outlet orifice from the reactor, to one or more other places.

A tubular reactor is preferably used in accordance with the present invention. In general, the tube of the tubular reactor is constructed in such a way that it has a sufficient length to ensure a sufficient duration of permanence in the reactor in order to chemically convert the components sufficiently in view of the flow rate of the reaction solution, its concentration as regards the reactants and the temperature of the reaction solution. An especially preferred reactor, which can be used in situ for the preparation of an appropriate aqueous chlorine dioxide generating compound, is a tubular reactor (regulated in terms of temperature), which contains one or more tubular coils. 7 10

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Persons specialized in the sector are in a position to vary the size and shape of the reactor depending on the amount of aqueous chlorine dioxide to be produced, the flow of circulation and the concentration of the reactants, the pH value of the aqueous reaction solution, the pH value of ClO2 and the reactor temperature. Persons specialized in the sector are also in a position to modify the reactor temperature in a corresponding manner.

The period of reaction time in the reaction room may vary. With an increasing concentration of the reactants in the reaction room the optimum value of the period of residence time is decreased. If a solution with a chlorine dioxide concentration of 20 g / l is prepared, the average period of residence in the reactor is approximately 60 minutes up to 4 minutes, preferably around 4 to 6 minutes, with in order to achieve a yield of approximately 85%. If the concentration of chlorine dioxide, according to the especially preferred embodiment, increases to a value greater than 80 g / l, then the average period of residence in the reactor is between approximately 0.1 minutes. up to 1.5 minutes, preferably in 0.3 to 0.6 minutes, especially preferably in about 0.4 minutes, to obtain a yield of 95%. The minimum value of the average period of residence can be achieved when the reactants are used in the form of concentrated solutions, the use of a dilution water is dispensed with and the necessary stoichiometric excess of an acid is minimized, or respectively of chlorine

Preferably, the value of the electrical conductivity is measured in the solution leaving the reaction room, before delivery thereof to the water to be treated. For example, an inductive measurement procedure can be used. From the values of the electrical conductivity that have been measured, information can be obtained about the chemical conversion of the reactants used as well as eventually about the amount of dilution water that has been used.

The dilution of the chlorine dioxide solution leaving the exit orifice from the reactor or the bypass line is carried out in such a way that the flow of renewal of the water to be treated in the exit orifice from the reactor is from about 0.1 m3 / h to 20 m3 / h of chlorine dioxide produced per gram and hour, preferably from 1 m3 / h to 4 m3 / h of chlorine dioxide produced per gram and hour.

The process according to the invention can be carried out, for example, by means of the devices shown in Figure 1 and Figure 2.

A structure of principle for carrying out the process according to the invention is shown in Figure 1, without being restricted to certain starting chemicals (reactants). Equipment with the indicated reference figure must therefore be used in their function in a correspondingly general manner for all procedures with the different possible starting chemicals (reactants) and are easily recognizable by a person skilled in the art.

In Fig. 1 the device for the treatment of water with chlorine dioxide is composed of two tanks for the starting chemicals (reactants), in particular a tank 1 for the storage of a chlorite with a conveyor pump 4 and a tank 2 for the storage of an acid with a conveyor pump 5. The water pump 6 is supplied through the water connection 3. The three conveyor pumps are connected, through an individual conduit, to the bottom of the reactor 7. Arrangements are located in the reactor according to the state of the art, which guarantee a complete and rapid mixing of the contributed components in the reaction room. By varying the concentration contents of the reactant solutions or the amount of dilution water that has been used, the concentration of the resulting chlorine dioxide solution is adjusted to a value greater than 3 g / l, so preferably greater than 26 g / l and especially preferably greater than 80 g / l ..

At the upper opposite end of the reactor 7 is located the outlet port 8 from the reactor, with which an arrangement 13 for measuring the electrical conductivity is previously connected.

In the passage of the chlorine dioxide solution to the water to be treated, a water tube pump 14 for liquids can be arranged, whereby the flow rate of water renewal to be treated can be increased. the entrance for chlorine dioxide. The supply line from the outlet orifice 8 from the reactor to the water tube pump 14 for liquids in this case has a discharge hole, which ensures that the water pressure 9 -which has been effective to treat - in the reactor 7.

The reactor is completely surrounded by water 9 - to be treated -, which circulates through an intermediate warehouse. The treated water is removed through a suction line from the intermediate warehouse and is supplied with the recirculation pump 10 to the site of use 11 of the water - which has been treated. Through a return line 12 the water 9 - which then has to be treated again - is returned to the intermediate warehouse, and passes again through the outlet orifice 8 from the reactor or through the exit site from the pump horn of

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water 14 for liquids. The outlet orifice 8 from the reactor can also be placed in local proximity with respect to the suction side of the recirculation pump 10, in order to ensure a rapid exchange of water 9 - to be treated - in the orifice 8 output from the reactor. An appropriate choice of the parameters "depth of immersion of the reactor in the water to be treated" (pressure) and "concentration of the solution of dioxide, of chlorine that has been produced in the reactor", taking into account the temperature of the water to be treated, as shown by way of example in Fig. 3, the formation of a gas phase of chlorine dioxide can be suppressed. Moreover, there is a possibility that the chlorine dioxide solution leaving the reactor 7 is transported through a bypass line that is located next to the outlet port 8 from the reactor (which is not shown in the Fig. 1) to one or more other sites. There may also be placed equipment for the distribution of the chlorine dioxide solution, eg the water tube pump for liquids, the recirculation pump, etc.

A structure of principle for carrying out the process according to the invention is shown in Figure 2 without being restricted to certain starting chemicals (reactants). The equipment with the indicated reference figures must therefore be used in their function in a correspondingly general manner for all procedures with the different starting chemicals (reactants) and are easily recognizable by a person skilled in the art.

Another preferred device for the process according to the invention is reproduced in Fig. 2. In this case, it is essential for the invention that the reaction enclosure is located within a tubular conduit 15, running the water to be treated. tubular conduction and the reaction enclosure being surrounded by the current of the water to be treated.

In Fig. 2 the reactor 7 is connected, in an identical manner to that in Fig. 1, with the same supply lines. The reactor 7 is also surrounded by the water 9 - which is to be treated - but the reactor 7 is located in a tubular conduit 14 which is surrounded by the water 9 - which is to be treated -, which contributes to the water 9 -which has to be treated - after having passed through the outlet hole 8 from the reactor, to the site of use 11 of the water - which has been treated.

In Fig. 2 the reactor 7 can also be supplied with a dilution water equal to that in Fig. 1, but a preferred variant consists in reacting in the reactor 7 without any dilution of the reactants by means of water in the enclosure of reaction (the transport pump for dilution water 6 being disconnected). In such a case, the concentration of the resulting solution in the outlet port 8 from the reactor may increase to a value greater than 9 g / l, [without dilution water, the ClO2 content, also in the case of use of 3.5% concentrated reactants, it preferably increases to 9.1 g / l], preferably greater than 26 g / l, and especially preferably greater than 80 g / l chlorine dioxide, per liter. In the case of this preferred variant, it is advantageous to minimize the magnitude of the reactor volume. As a general rule, no other arrangements are needed to increase the rate of renewal of the water 9 - to be treated - in the outlet port 8 from the reactor, in order to shift the concentration of the chlorine dioxide solution, then of the entry into the water 9 - to be treated -, quickly from a value preferably greater than 80 g / liter to the region of milligrams. Also, as a general rule, it is not difficult to adjust the water pressure 9 - to be treated - in the tubular conduit 14 in such a way that the solubility limit of chlorine dioxide in the aqueous solution that is inside is not exceeded. of reactor 7, as depicted in Fig. 3.

Legends of Fig. 1 and Fig. 2:

1 Tank for the storage of a chlorite 2 Tank for the storage of an acid 3 Connection for water 4 Pump for the transport of the chlorite 5 Pump for the transport of the acid 6 Pump for the transport of the dilution water 7 Reactor (reaction room) 8 Exit orifice from the reactor 9 Water to be treated 10 Recirculation pump for the water that has been treated 11 Site of use of the water that has been treated 12 Conduction of return of the water to be treated 13 Measurement provision of electrical conductivity 14 Water tube pump for liquids, optional 15 Tubular conduction in Figure 2.

Figure 3 shows the limits of solubility of chlorine dioxide in an aqueous solution, depending on pressure and temperature, by way of example for chlorine dioxide concentrations of 70 g / l and 80 g / l.

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The process according to the invention is explained by the following Examples:

Example 1

The device described in Fig. 1 is used. The aqueous solution in the tank 1 for the storage of a chlorite contains 25% sodium chlorite and with the conveyor pump 4, 2.5 l / h are moved. this solution inside the reactor 7. From the tank 2 for the storage of an acid, 2.5 l / h of a 32% aqueous solution of hydrochloric acid are supplied at the same time with the conveyor pump 5 to the reactor 7. A through the amount of the dilution water of 5 l / h, which is also provided at the same time with the conveyor pump 6 to the reactor 7 from the water connection 3, the concentration of the resulting chlorine dioxide solution is adjusted to 42 g / l [in the case of a yield of 92%]. The reactor has a free volume of 0.33 liters and the period of residence of the reaction mixture in the reaction room is 2 minutes. 10 liters of the chlorine dioxide solution, with a content of 42 g / l, is supplied every hour through the outlet hole 8 from the reactor to a water tube pump 14 for liquids, which is operated with the water to be treated, and then mixed with the amount returned of the water to be treated. The value that is determined with the electrical conductivity measurement system 13 is 0.42 S / cm. 1,000 m3 of the water enriched with chlorine dioxide is removed every hour by the pump 10 for the recirculation of the treated water from the intermediate warehouse and made available to the site 11 for the use of the water that has been treated. Through the return line 12 of the water to be treated, the water impoverished with chlorine dioxide returns to the intermediate store. On the way to the suction site of the treated water recirculation pump 10, the water to be treated picks up the outgoing water containing chlorine dioxide and in such case reduces the concentration of chlorine dioxide in the mixed water, quickly, at 0.42 mg / l. The outlet port 8 from the reactor is submerged in the intermediate warehouse 4 meters below the water surface and the temperature of the water to be treated is 32 ° C. In the case of the devices described in Example 1 it is, in the case of the water to be treated 9, a retrocooling water of a circulating cooling system, which is located in a cup of a tower of refrigeration (intermediate warehouse). With the recirculation pump 10, the cooling water is conducted through heat exchange surfaces of a chemical production facility with exothermic heat sources (the water use site 11 - which has been treated -) already It is then drained on the internal constructions of an evaporation cooling tower, before it reaches the cooling tower (intermediate storage). The cup of the cooling tower has a volume of 800 m3. The level of water in the intermediate warehouse is regulated in terms of the level, so that the cooling water that evaporates is automatically replaced by a fresh water.

Example 2

The device described in Fig. 2 is used. The aqueous solution in the tank 1 for the storage of a chlorite contains 25% sodium chlorite and with the conveyor pump 4 6 l / h of this solution are moved to the reactor 7. From the tank 2 for the storage of an acid, 5 l / h of a 30% aqueous solution of hydrochloric acid are supplied to the reactor 7 at the same time. The reactor 7 is mounted within a tubular conduit 14, which is traveled by an amount of 100 m3 of water 9 - which has to be treated - per hour. Through the conveyor pump 6, no dilution water is supplied to the reactor. The reactor has a free volume of 0.075 books and the period of residence of the reaction mixture in the reaction room is 0.4 minutes. 11 liters of a solution of chlorine dioxide having a content of 94 g / l are delivered every hour, through the orifice 8 from the reactor, to the water 9 - to be treated - which circulates around the reactor 7, whereby the concentration of the reaction mixture in the outlet port 8 from the reactor is suddenly reduced to 10 mg / l by mixing with the water 9 - to be treated -. In the case of an excess of 300% acid, chlorine dioxide is produced with a yield of 95%. The water pressure 9 - to be treated - in the tubular conduit 14 is 5.5 bar and its renewal flow in the outlet hole 8 from the reactor is located at 0.1 m3 / h of chlorine dioxide produced per gram and hour. Water 11 - which has been treated - is made available to the site of use at the end of the tubular conduit. In the case of the provisions described in Example 2, this is the treatment of 100 m3 / h of a wash water, which is used in a cleaning facility with a chlorine dioxide concentration of 10 mg / l.

Example 3

The device described in Fig. 1 is used. The aqueous solution in the tank 1 for the storage of a chlorite contains 24.5% of sodium chlorite and with the conveyor pump 4, 5 l / h are moved. this solution to the reactor 7. From the tank 2 for the storage of an acid, 5 l / h of a 32% aqueous solution of hydrochloric acid are supplied with the conveyor pump 5 to the reactor 7. Through the amount of dilution water of 28 l / h that is supplied to the reactor 7 with the conveyor pump 6 from the water connection 3, the concentration of the resulting chlorine dioxide solution is adjusted to 19.7 g / l [in the case of a 83% yield]. The reactor has a free volume of 6 liters and the period of residence of the reaction mixture in the reaction room is 9.5 minutes. 38 liters of the chlorine dioxide solution with a

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19.7 g / l content is delivered per hour through the outlet hole 8 from the reactor, which is located

in the proximity of the suction line of the recirculation pump 10, to the water 9 -that is to be treated -that

surrounds the reactor. 2,000 m3 of the water enriched with chlorine dioxide is removed every hour by the pump

water recirculation 10 - which has been treated - from the intermediate warehouse and made available to site 11 of

5 water use - which has been treated -. Through the return water conduction 12 -which has to be

treated - water depleted with chlorine dioxide returns to the intermediate warehouse. On the way to the site of

suction of the water recirculation pump 10 -that has been treated -water absorbs the water it contains

Chlorine dioxide that exits through the orifice 8 from the reactor and quickly reduces the concentration in that case

of chlorine dioxide in the mixed water to below the critical concentration of 6 g / l. In front of site 11 of 10 water utilization - which has been treated - the concentration of chlorine dioxide is approximately

0.4 mg per liter of water.

Claims (19)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty E08861135 11-27-2014 1. Procedure for the treatment of water with chlorine dioxide (ClO2), characterized by the characteristics that

one.

the reaction room, in which ClO2 is produced, is completely surrounded by water,

2.

the water surrounding the reaction room is at the same time the water to be treated,

3.

The ClO2 resulting in the reaction room is displaced from the reaction room directly to the water

to be treated, the reaction room being a reactor, which is operated without any pressure regulation arrangement, and the reactor having a free outlet located in the outlet orifice from the reactor, such that the Pressure in the reaction room can only rise to the value that is exerted by the surrounding water on the reaction room.

2.

Process according to at least one of the preceding claims, characterized in that, the reactor is a tubular reactor.

3.

 Process according to at least one of the preceding claims, characterized in that, the reaction time period of the reactants in the reaction room varies from 4 to 60 minutes, preferably from 4 to 6 minutes, especially preferably from 0.1 to 1.5 minutes and very especially preferably from 0.3 minutes to 0.6 minutes.

Four.

Process according to at least one of the preceding claims, characterized in that the chlorine dioxide is produced from a chlorite salt of an alkali metal and hydrochloric acid (reactants).

5.

 Process according to at least one of the preceding claims, characterized in that the chlorine dioxide is produced from sodium chlorite and hydrochloric acid (reactants).

6.

 Process according to at least one of the preceding claims, characterized in that the chlorine dioxide is produced from sodium chlorite in a 3.5% to 40% aqueous solution.

7.

 Process according to at least one of the preceding claims, characterized in that the chlorine dioxide is produced from hydrochloric acid in a concentration of from 3.5% to 42%.

8.

 Process according to at least one of the preceding claims, characterized in that the chlorine dioxide is produced from sodium chlorite and chlorine (reactants).

9.

 Method according to at least one of the preceding claims, characterized in that the value of the electrical conductivity is measured in the solution leaving the reaction room.

10.

Method according to at least one of the preceding claims, characterized in that the reaction chamber is located within a tubular conduit and the tubular conduction is traversed by the water to be treated.

eleven.

 Process according to at least one of the preceding claims, with a dilution of the chlorine dioxide solution leaving the outlet orifice from the reactor in such a way that the rate of renewal of the water to be treated in the outlet orifice from the reactor is from about 0.1 m3 / h to 20 m3 / h of chlorine dioxide produced per gram and hour, preferably from 1 m3 / h to 4 m3 / h of chlorine dioxide produced per gram and hour.

12 E08861135 11-27-2014 12. Process according to at least one of the preceding claims, the combination of the concentrations of the starting chemicals and the dilution water being chosen which is eventually used in such a way that the concentration of the chlorine dioxide formed is chosen. in the outlet orifice from the reactor it is located at a value greater than 3 g / l of the solution, preferably greater than 26 g / l 5 of the solution and especially preferably at a value greater than 80 g / l of the solution. 13. Method according to at least one of the preceding claims, characterized by the characteristics that 1. the water surrounding the reaction room exerts on the solution containing chlorine dioxide in the room 10 a pressure with a magnitude such that the solubility limit of chlorine dioxide in water at the given temperature is not exceeded, 2. The combination of the concentrations of the starting chemicals and the dilution water that is eventually used is chosen in such a way that the concentration of chlorine dioxide formed in the outlet orifice from the reactor is situated at a value greater than 3 g / l of the solution, preferably 15 greater than 26 g / l of the solution and especially preferably at a value greater than 80 g / l of the solution. 14. Process according to at least one of the preceding claims, characterized in that concentrated starting chemicals are used and worked according to the process with 20 hydrochloric acid and a chlorite (1) the concentration of hydrochloric acid being 33-42% and that of sodium chlorite solution being 25-40%. 15. Method according to at least one of the preceding claims, characterized in that, The ClO2 resulting in the reaction room is not directly displaced from the reaction room to the water to be treated, but the chlorine dioxide solution leaving the reaction room is transported through a conduit. bypass that is located at the end of the reaction room (exit hole) to one or more other sites. 16. Procedure according to at least one of the preceding claims, 30 characterized in that, in the case to be treated, it is a retrorefigeration water of a circulating cooling arrangement, which is located in a cup of a cooling tower (intermediate storage). 13